This application is in response to the NIAAA program announcement (PA-08-169) on Secondary Analysis of Existing Alcohol Epidemiology Data. The overarching goal of this application is to enhance our understanding of the longitudinal patterns and trends of alcohol use among methamphetamine and cocaine users. Most prior research on the epidemiology of alcohol and stimulant use has relied on data from cross-sectional surveys or treatment-based samples. There is very little information about the natural history of alcohol use among community-based samples of stimulant users, particularly methamphetamine users, many of whom do not access formal substance abuse services. Of key concern is whether alcohol is used a complement or substitute to cocaine and/or methamphetamine over time and whether cocaine and/or methamphetamine use is associated with the risk of developing/maintaining or remitting from an alcohol use disorder (AUD). To address these issues, we propose to conduct extensive secondary statistical analyses of alcohol-related data collected as part of the NIDA-funded Rural Stimulant Study (RSS). The RSS is a very unique multi-state, community-based, and longitudinal (7 interviews over 3 years) natural history study of 710 persons who were recent or current users of cocaine and/or methamphetamine at the time of study enrollment. While numerous measures of the frequency and quantity of alcohol use as well as diagnoses of alcohol use disorders (AUDs) were assessed at 6-month intervals as part of the RSS, the original grant did not contain any specific aims or hypotheses pertaining to alcohol. Our specific research aims are to (1) Investigate the natural history of alcohol use and potential substitution of cocaine and/or methamphetamine with alcohol over time and (2) Investigate the longitudinal relationships between cocaine and MA use and the risk of an alcohol use disorder (AUD). We have chosen to focus this R03 application on these aims because they represent important unanswered questions and do not fall within the aims of the original parent study. An additional strength of the proposed study is that the sample is comprised of stimulant users residing in rural areas, a subpopulation that is historically understudied and underrepresented in substance abuse research. In summary, the proposed study will afford us the opportunity to conduct quantitative analyses of a unique data set and thus advance our understanding of the longitudinal interplay between alcohol and stimulant use in a very cost effective manner. The research findings have the potential to contribute to improvements in alcohol use prevention and treatment among current or past stimulant users. PUBLIC HEALTH RELEVANCE: The proposed research has important public health significance regarding alcohol and stimulant use, particularly in rural America, which is experiencing a rapid increase in the use of cocaine and methamphetamine. Further understanding of the interplay between alcohol and stimulant use over time, including whether alcohol is used as a substitute for cocaine and/or methamphetamine, could contribute to improvements in substance abuse prevention and treatment.